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241.
A robust fringe-shifting and image processing scheme is applied to geometric moiré experiments. High quality contour maps
ofU, V andW displacement fields are obtained with sensitivity enhanced by a factor of ten. The method is compatible with complicated
intensity distributions, variable bar-to-space ratios of gratings, and optical noise. It is applicable to large fields for
both in-plane moiré and shadow moiré measurements.
Paper was presented at the 1992 SEM VII International Congress on Experimental Mechanics held in Las Vegas, NV on June 8. 相似文献
242.
E.J. Post 《Physics letters. A》1983,94(8):343-345
The quantized Hall impedence is shown to relate to the ratio of two period integrals which are identified as the familiar period integrals of flux and electric charge if their domain of definition is extended to the realm of spacetime. 相似文献
243.
244.
Guilherme Post Sabin Werickson Fortunato de Carvalho Rocha Ronei Jesus Poppi 《Microchemical Journal》2011,99(2):542-547
Nowadays, near-infrared spectroscopy chemical imaging (NIR-CI) has been widely used in pharmaceutical analysis since it provides important surface information about the samples. In this work the information of NIR-CI at the pixel level was compared through calculation of the similarity between distribution maps of concentration obtained by different multivariate calibration approaches. The comparison was performed by using four different multivariate methods (MCR, MLR, CLS and PLS) in analysis of carbamazepine pharmaceutical formulations. For global determination, all models developed showed RMSEP below 1.9% (w/w) for active principal ingredient (API) and better than 4.6% (w/w) for excipients. Also, the distribution maps obtained by PLS, CLS and MCR showed great similarity for all compounds of the formulation as well with concentrations in the tablets. However, comparing the distribution maps obtained by MLR with those from the other chemometric tools, a lower similarity was observed. Thus, this fitted model does not ensure, by itself, that the images obtained are reliable or accurate. The paper also compares the distribution maps of concentrations obtained from all constituents present in the pharmaceutical formulation with their respective micrographs. 相似文献
245.
Jackson SN Ugarov M Post JD Egan T Langlais D Schultz JA Woods AS 《Journal of the American Society for Mass Spectrometry》2008,19(11):1655-1662
Combining matrix-assisted laser desorption/ionization (MALDI) mass spectrometry with ion mobility (IM) results in the fast
sorting of biomolecules in complex mixtures along trend lines. In this two-dimensional (2D) analysis of biological families,
lipids, peptides, and nucleotides are separated from each other by differences in their ion mobility drift times in a timescale
of hundreds of microseconds. Molecular ions of similar chemical type fall along trend lines when plotted in 2D plots of ion
mobility drift time as a function of m/z. In this study, MALDI-IM MS is used to analyze species from all of the major phospholipid classes. Complex samples, including
tissue extracts and sections, were probed to demonstrate the effects that radyl chain length, degree of unsaturation, and
class/head group have upon an ion’s cross section in the gas phase. We illustrate how these changes can be used to identify
individual lipid species in complex mixtures, as well as the effects of cationization on ion cross section and ionization
efficiency. 相似文献
246.
Leandro Wang Hantao Helga Gabriela Aleme Marcio Pozzobon Pedroso Guilherme Post Sabin Ronei Jesus Poppi Fabio Augusto 《Analytica chimica acta》2012
This review describes the major advantages and pitfalls of iterative and non-iterative multivariate curve resolution (MCR) methods combined with gas chromatography (GC) data using literature published since 2000 and highlighting the most important combinations of GC coupled to mass spectrometry (GC–MS) and comprehensive two-dimensional gas chromatography with flame ionization detection (GC × GC-FID) and coupled to mass spectrometry (GC × GC–MS). In addition, a brief summary of some pre-processing strategies will be discussed to correct common issues in GC, such as retention time shifts and baseline/background contributions. Additionally, algorithms such as evolving factor analysis (EFA), heuristic evolving latent projection (HELP), subwindow factor analysis (SFA), multivariate curve resolution-alternating least squares (MCR-ALS), positive matrix factorization (PMF), iterative target transformation factor analysis (ITTFA) and orthogonal projection resolution (OPR) will be described in this paper. Even more, examples of applications to food chemistry, lipidomics and medicinal chemistry, as well as in essential oil research, will be shown. Lastly, a brief illustration of the MCR method hierarchy will also be presented. 相似文献
247.
Gerhard Post Samad Ahmadi Sophia Daskalaki Jeffrey H. Kingston Jari Kyngas Cimmo Nurmi David Ranson 《Annals of Operations Research》2012,194(1):385-397
The High School Timetabling Problem is amongst the most widely used timetabling problems. This problem has varying structures
in different high schools even within the same country or educational system. Due to lack of standard benchmarks and data
formats this problem has been studied less than other timetabling problems in the literature. In this paper we describe the
High School Timetabling Problem in several countries in order to find a common set of constraints and objectives. Our main
goal is to provide exchangeable benchmarks for this problem. To achieve this we propose a standard data format suitable for
different countries and educational systems, defined by an XML schema. The schema and datasets are available online. 相似文献
248.
Olaf Post 《Annales Henri Poincare》2009,10(5):823-866
The aim of the present paper is to introduce a unified notion of Laplacians on discrete and metric graphs. In order to cover
all self-adjoint vertex conditions for the associated metric graph Laplacian, we develop systematically a new type of discrete
graph operators acting on a decorated graph. The decoration at each vertex of degree d is given by a subspace of , generalising the fact that a function on the standard vertex space has only a scalar value. We illustrate the abstract concept
by giving classical examples throughout the article. Our approach includes infinite graphs as well. We develop the notion
of exterior derivative, differential forms, Dirac and Laplace operators in the discrete and metric case, using a supersymmetric
framework. We calculate the (supersymmetric) index of the discrete Dirac operator generalising the standard index formula
involving the Euler characteristic of a graph. Finally, we show that for finite graphs, the corresponding index for the metric
Dirac operator agrees with the discrete one. 相似文献